Network-based retailers and merchants often offer thousands of items (e.g., goods and/or services) for browsing, purchasing, or otherwise selecting from an electronic catalog. The contents of an electronic catalog may change frequently as new items are added, item descriptions change, and current items sell out or become unavailable. Such items may be classified as belonging to one or more categories. Potential buyers typically browse such items though an item search engine or through indexes of the items within categories. An incorrect and/or incomplete classification of items may hinder discovery of items in the electronic catalog.